Fel Undulator Technology And Synchrotron Radiation Source Requirements

This paper describes design and construction considerations of the THUNDER undulator, for use in free electron laser experiments at visible wavelengths. For the parameters of these experiments, an unusually high degree of optimization of the electron photon interaction is required and, as a result, THUNDER is built to especially high mechanical and magnetic precision. Except for its narrow magnet gap, the 5 meter THUNDER undulator is quite similar to insertion devices under consideration for the proposed 6 GeV storage ring. The engineering and physics approach adopted for this FEL modulator design is directly applicable to insertion device development. The tolerance limits to THUNDER, established by modeling and design and achieved through careful control of mechanical and magnetic errors, are essential to the next generation of insertion devices.